The present invention relates to a radiation thermometer.
For the purpose of measuring a body temperature in a short period of time, a radiation thermometer which selects an eardrum as a measurement site and measures a temperature of the eardrum in a non-contact manner has been already proposed.
An example is a radiation thermometer which is described in Japanese Laid-Open Patent Publication No. 28524/1990. This radiation thermometer allows a front end of a probe portion, which comprises a window member at a front end and an infrared ray sensor at a rear end, to be inserted into an external acoustic opening, so that an infrared ray from the eardrum is received by the infrared ray sensor through the window member and the temperature of the eardrum, i.e., the body temperature, is measured based on the intensity of the received infrared ray.
Since this type of radiation thermometer measures a body temperature based on the intensity of an infrared ray from the eardrum, the dirtiness of the optical system which receives the infrared ray has influence on measurement accuracy. However, an external acoustic opening becomes dirty because of earwax and the like, and therefore, measuring a body temperature several times causes a problem in that the window member serving as an optical system of the front end of the probe portion is gradually smudged. Further, it is unhygienic where more than one person shares the same radiation thermometer.
To solve this problem, the radiation thermometer described in Japanese Laid-Open Patent Publication No. 28524/1990 comprises a probe cover designed to cover the front end of the probe portion which is inserted into an external acoustic opening. The probe cover prevents the probe portion of the radiation thermometer from directly contacting the external acoustic opening. In addition, since the probe cover is disposable for each measurement of a body temperature, there is no problem in that a dirty optical system deteriorates a measurement accuracy, and there is no hygienic problem.
However, when a probe cover is used as in the case of the radiation thermometer described in Japanese Laid-Open Patent Publication No. 28524/1990 described above, a new probe cover is necessary each time a body temperature is measured, which is costly. Hospitals, in particular, which need to measure body temperatures frequently must bear a considerable running cost.
Further, since a conventional radiation thermometer which uses probe covers requires discarding the probe cover each time a body temperature is measured, it is necessary to procure new probe covers often, which is labor-consuming.
The present invention has been made in view of the problems above. Accordingly, an object of the present invention is to provide a radiation thermometer which prevents deterioration of measurement accuracy and loss of hygiene due to a smudged front end of a probe portion, reduces running costs which are created by use of the probe cover and omits the labor of procuring a probe cover.
To attain the object above, a radiation thermometer of the present invention comprises: a window member which transmits an infrared ray; light-guiding means for guiding the infrared ray which is transmitted by the window member from a measurement target; an infrared ray sensor for detecting the infrared ray which is guided by the light-guiding means; a temperature-sensitive sensor for measuring a reference temperature and generating a reference temperature signal; a case means which covers at least the light-guiding means, an infrared ray sensor and a temperature-sensitive sensor which comprises a probe portion which is inserted into an opening of a living being; a temperature calculating means for calculating a temperature of the measurement target based on signals from the infrared ray sensor and the temperature-sensitive sensor; and an indicating means for indicating a temperature based on a signal from the temperature calculating means, characterized in that at least the probe portion comprises waterproof means.
The probe portion comprises at least an opening portion in which only an infrared ray introducing side of the light-guiding means is exposed, and the waterproof means is a waterproof member which waterproofs a gap between the light-guiding means and the probe portion located at the opening portion.
The waterproof member includes a holding member which fits with an outer periphery of the light-guiding means, and holds the window member in the vicinity of the opening portion; a first packing which between the holding member and the probe portion; and a second packing arranged between the holding member and the light-guiding means.
The holding member comprises a pressuring portion which presses and holds the window member towards the light-guiding means, and the window member is firmly held by the pressuring portion and the second packing.
The light-guiding means is formed by a light-guiding tube, and the holding member comprises a monolithically integrated engagement portion which fits with an outer surface of the light-guiding tube.
The light-guiding tube comprises a stepped portion for attaching the second packing to a front end portion of the light-guiding tube.
The holding member comprises an abutting portion for abutting against the stepped portion for the purpose of positioning, the window member is firmly held between the holding member and the second packing with the abutting portion abutting the stepped portion, and a gap is provided between the window member and the front end portion of the light-guiding tube.
The second packing protrudes beyond the front end portion of the light-guiding tube, and the window member is firmly held between the holding member and the second packing.
The holding member comprises a concave portion for positioning the first or the second packing.
The radiation thermometer further comprises a temperature difference information detecting means for detecting temperature difference information regarding the infrared ray sensor and the light-guiding means, wherein the temperature calculating means calculates a temperature of the measurement target based on signals from the infrared ray sensor and the temperature-sensitive sensor and the temperature difference information received from the temperature difference information detecting means.
The temperature difference information detecting means is formed by: a first temperature-sensitive sensor for measuring a temperature of the infrared ray sensor and an area around the same; and a second temperature-sensitive sensor for measuring a temperature of the light-guiding means.
The temperature difference information detecting means is formed by: a reference cavity whose temperature condition is approximately the same as a temperature condition of the light-guiding means and which is closed whereby infrared rays from outside does not enter; and a reference infrared ray sensor for detecting an infrared ray from the reference cavity.
The window member is formed by an optical crystal material.
The optical crystal material is calcium fluoride, silicon, antireflection silicon, or barium fluoride.
A heat insulation cavity is provided between the probe portion and the light-guiding tube.
The light-guiding means, the infrared ray sensor and the temperature-sensitive sensor are linked to each other by a metal housing which has excellent thermal conductivity.